1. Field of the Invention
The present invention relates to a belt type continuously variable transmission for transmitting the revolution of an input shaft to an output shaft by changing the revolution ratio steplessly and, in particular, to the structure of a movable rotor for supporting a radial load and of a revolving shaft onto which the movable rotor is fit in a manner inhibiting their relative rotation and allowing axial displacement.
2. Description of Related Art
A belt type continuously variable transmission for vehicles comprises: a pair of revolving shafts mutually in parallel; a primary-side sheave (input-side pulley) supported in a revolvable manner by the revolving shaft on the input side and having an adjustable groove width; a secondary-side sheave (output-side pulley) identically supported in a revolvable manner by the revolving shaft on the output side and having an adjustable groove width; and a drive belt wound around the primary-side sheave and the secondary-side sheave constituting the above-mentioned pair, whereby the effective diameter of the primary-side sheave and the effective diameter of the secondary-side sheave are varied so that the revolution ratio is varied steplessly.
For example, each of the above-mentioned sheaves comprises: a fixed rotor fixed to the revolving shaft in a manner inhibiting their relative displacement; and a movable rotor fit onto the revolving shaft in a manner inhibiting their relative rotation and allowing relative axial displacement, whereby when the movable rotor is moved in an axial direction so that the distance to the fixed rotor is varied, then the groove width is varied so that the wind-around diameter, that is, the effective diameter, of the drive belt is varied.
In the connection (linkage) between the above-mentioned movable rotor and the revolving shaft, ball splines are used in general. Nevertheless, such a fit structure via ball splines results in a high cost. Thus, methods have been proposed for fitting a movable rotor onto a revolving shaft in a manner inhibiting their relative rotation and allowing relative axial displacement without the use of ball splines. An example is given in Japanese Published Unexamined Patent Application No. H6-341500.